Unable to insert categories via forum connection

Hello,

I have a problem that it is not possible to connect the category through the connection to "for example, where to insert as together so that it can be known as phpBB 3 but unfortunately without success. Please fix my forum topic of my admin panel "connection to" because an error occurred. It is necessary to fix them necessary. Thank you very much. I am deaf, I live in Brno, Czechia.

My forum:
https://allforum.forumotion.eu/

Good evening!

I don't understand Czech language, but I think you are trying to move the forum into its subforum. Or a category in the forum. This causes an error.
I think it would be useful for you to read these tutorials first:

Run through of the admin panel
Differences between Forum and Category
Categories and Forums - Creation and Appearance

Solved, they were looking for Categories and Forums - Creation and Appearance, thanks for the instructions, happy. First, Categories and Forums - Creation and Appearance, then click "Medium". We have success.