/Applicationsis only writable by admin users:
% ls -ld /Applications drwxrwxr-x+ 65 root admin 2080 10 Jan 08:02 /Applications
If you want to install or update apps there, you’ll need to either limit yourself to running as an admin user  or implement some sort of privilege escalation.
IMPORTANT Modifying apps is a tricky business:
Never work on the in-place copy of the app. Rather, make a copy, work on that, and then replace the original with your copy.
You have to make sure that your final version is correctly signed and notarised.
/Library/Application Supportis not writeable even by admin users. You’ll definitely need to escalate privileges to operate there.
% ls -ld /Library/Application\ Support drwxr-xr-x 25 root admin 800 29 Dec 13:21 /Library/Application Support
Share and Enjoy
Quinn “The Eskimo!”
Apple Developer Relations, Developer Technical Support, Core OS/Hardware
let myEmail = "eskimo" + "1" + "@apple.com"
 I don’t recommend that. A common pattern is for folks to create an admin account and a standard account and then run as the standard user day-to-day. If they need to do admin-y stuff, they simply authenticate using their admin account.