Hello new user MADMAX300 ... one have to understand, that Mp3tag in its listview user interface does work on physical existing files, ... and therefore it can do auto numbering of files, but not auto numbering of folders or album sets.
Well, it is not impossible at all, when the user is willing to learn the MTE export scripting language.
While creating a textual export out file, one can code the numbering of folders or album sets, for each related file.
When the export output text has been created, for example in the format CSV, then such calculated values can be imported back into tag-fields for each file.
You have to try out for yourself how the entire process will work.
There is a thread, which may help to understand, how your wish could be realized.
/t/12054/1
DD.20171129.2022.CET