Creating new actions on Mac

[ohrenkino]

And where in this long list of instructions did you get stuck?

To me it looks like AI-generated.
And at least this part

@iAutobot

• $num(%_createtime%,1)*
• This function will assign track numbers based on the creation date of the files. The "%_createtime%" variable represents the file's creation date/time, and the "1" parameter specifies the starting track number.*

does not look like being from MP3tag.
See here for available placeholders for properties:

Format Strings and Available Placeholders

Mp3tag uses format strings in various of its features to describe the structure of file names and imported data. A format string is built of either standard text (e.g., Music), placeholders (such as %artist%, %title%, ...), or slash characters / that usually denote directory structures. Characters with Special Functionality Some characters have special functionality and need to be treated with extra care. If you experience some unexpected behavior when using format string, check if some of t…

where I do not find a placeholder %_createtime% but only %_file_create_date% (and others).
See here for the correct use of $num()

Scripting Functions

Mp3tag offers various built-in scripting functions, which can be used at various places in the program. These functions offer advanced display and converting options and are to be used in combination with Format Strings and Available Placeholders. General Functions Replace $replace(string,from,to) or $replace(string,from1,to1,from2,to2,...) Example: $replace(%title%,_,-) This example replaces all underscores with dashes. You can provide additional pairs of from/to as parameters. Case Co…

which does not feature a starting value.

So it would help if you could show us a real example of the data what it looked like for a start, then what it should look like after the modification and the function with which you tried to achieve the modification.