I only mentioned the macbook in case the type of machine I'm playing on might be relevant to the problem/solution. I am very grateful for any help. Here's what I did step by step:
Downloaded the Mustermann skin from here:https://www.fmscout.com/a-mustermann-iconic-fm24-skin.html
Extracted the folders from the .rar.
Placed two folders, "Mustermann Iconic 1.1" and "Mustermann Iconic Alt Files" in the Football Manager 2024 'skins' folder.
Opened FM24. Went to Preferences -> Advanced -> Interface
Selected Mustermann Iconic from dropdown.
Unchecked “Use caching to decrease page loading times” and ticked “Reload skin when confirming changes to preferences”.
Hit confirm.
Quit and reopened FM24.
Went to preferences and ticked “Use caching to decrease page loading times” and ticked "Reload skin when confirming..." then confirmed.
The skin is loaded and looks great. Only the 'profile' and 'attributes' pages show up empty.