OnlyOffice 9.1.0.173 Unlimited Build ( Debian 11 )

Make sure to install and check that the default deb binary from OnlyOffice repo works for you.
Then install this deb on your system thanks to:

apt install /path/to/onlyoffice-documentserver_9.1.0-173-btactic_amd64.deb

OnlyOffice 9.0.4.52 Unlimited Build ( Debian 11 )

Make sure to install and check that the default deb binary from OnlyOffice repo works for you.
Then install this deb on your system thanks to:

apt install /path/to/onlyoffice-documentserver_9.0.4-52-btactic_amd64.deb

OnlyOffice 8.1.3.3 Unlimited Build ( Debian 11 )

Make sure to install and check that the default deb binary from OnlyOffice repo works for you.
Then install this deb on your system thanks to:

apt install /path/to/onlyoffice-documentserver_8.1.3-3-btactic_amd64.deb

OnlyOffice 8.0.1.31 Unlimited Build ( Debian 11 )

Make sure to install and check that the default deb binary from OnlyOffice repo works for you.
Then install this deb on your system thanks to:

apt install /path/to/onlyoffice-documentserver_8.0.1-31-btactic_amd64.deb