To use the DataContainer project, the first thing you have to do is build the generator which turns the text file that determines what the data container will hold into the C++ header file that implements it. In Visual Studio you can do this by building the DataContainerGenerator sub-project (either in release or debug). If you aren't using Visual Studio, building the project is still easy: throw the .cpp and .hpp files from the DataContainerGenerator directory together and build them in whatever way you prefer; there are no dependencies except the standard library and no requirements except C++17 support.
Once you have compiled the generator and written a specification file describing your data container, it is time to figure out how to turn that file into a C++ header. In Visual Studio you can do this with a custom build tool. First, right click on the project within your solution that you want to generate the data container for and select Add > Existing Item to add the text file that you have written. Then, right click on the text file to view its properties. First find the Item Type property and change its value from Text to Custom Build Tool. After hitting apply, you should see new properties appear (under Custom Build Tool > General on the left). Change the Command Line setting to 𝘸𝘩𝘦𝘳𝘦 𝘺𝘰𝘶 𝘣𝘶𝘪𝘭𝘵 𝘵𝘩𝘦 𝘨𝘦𝘯𝘦𝘳𝘢𝘵𝘰𝘳\DataContainerGenerator 𝘺𝘰𝘶𝘳 𝘧𝘪𝘭𝘦 𝘯𝘢𝘮𝘦.txt. Change the Outputs property to 𝘺𝘰𝘶𝘳 𝘧𝘪𝘭𝘦 𝘯𝘢𝘮𝘦.hpp, and change Add Outputs to Item Type to C/C++ header. Don't forget to set these properties for both the debug and release configurations. Finally, right click on the specification file again and select Compile to make sure that you have done everything correctly. If you have, you can use Add > Existing Item again to make the generated header file part of the project.
If you are using CMake ... I don't use CMake myself, but my understanding is that you can use add_custom_command to run the generator.
For Meson ... probably custom_target will do the trick.
If you use either CMake or Meson, please feel free to contribute detailed instructions for them.
Once you have generated the header file for your data container, there are a few final things you need to do before you can successfully compile and use it. First, you will need to include the common_types.hpp file in your project (found in the CommonIncludes directory). Second, you will need ve.hpp and the other ve_....hpp header files, as described in the documentation for using the ve library. If you don't want to use the ve library, simply define DCON_NO_VE before including either the generated file or common_types.hpp. Finally, if you have declared one or more composite keys, (see composite keys) you will need to include the unordered_dense.h file from CommonIncludes in your project. This is a copy, provided for the sake of convenience, of the hash map header from Martin Leitner-Ankerl's unordered_dense project, and you may want to go directly to the source for a more up-to-date version. These files are all simple enough that I suggest just making copies of them and dropping them into your project directly, rather than trying to depend on DataContainer in some way (and I don't support that approach anyways).
Also, don't forget to define NDEBUG for your release versions, which not only turns off the standard C asserts, but will also direct the compiler to force inline the trivial functions (the intent is to help the compiler see through them).
The generated data container files require at least C++17 support to use, and are intended to work for msvc, clang, and gcc (there are a few compiler extensions used). I test almost exclusively with msvc, so if you encounter issues elsewhere, please let me know. In particular, the alignment of the data_container class is defined to be larger than the standard types. new in C++17 and later, as well as std::make_unique and std::make_shared, should support this over-alignment, but you may want to double check to make sure that the requested alignment is being respected.