Media type for Zabbix to send alerts to Nextcloud Talk
First of all you will need to create new user in your Nextcloud instance, that will send alerts.
Login to created user in previous step, open Talk, create chatroom, invite contacts who will recieve alerts and note room ID. You can create as chatrooms as you like.
Go to Zabbix -> Alerts -> Media Types -> Import and select zbx_nextcloud_mediatype.yaml
Open media type and enter username and password created in first step and change serverurl to match yours Nextcloud.
...just replace sendto parameter with your room ID from step 2
In Zabbix open Users -> Users, select user which should receive alerts, click Media -> Add, as Media Type select Nextcloud and to Send to type room ID from step 2.
That's all :)