There are many different ways to receive support for your Nextcloud installation, as it's explained deeply by the official Nextcloud blog post available here:

https://nextcloud.com/blog/are-you-an-enterprise-or-private-user-8-ways-to-get-help-for-any-nextcloud-matter/

AmberPRO also makes possible to receive support directly on your amber with Support Anywhere.

For additional information regarding Support Anywhere consult the manuals in the support page below, it also includes contacts!

Amber support: https://amberpro.net/support