I want to create a script in script editor that will press a key and then press enter every 60 seconds
How to send enter key using Applescript

In order to send the enter key in applescript you can use:

tell application "System Events"
  key code 36
end tell


Alternatively:

tell application "System Events"
  key code 76
end tell


The Difference between the two:

As shown here key code 36 is used to send the key Return. 

key code 76 on the other hand is used to send Enter.

(@user3439894 Pointed out that key code 36 is typically used.)

Fixing Applescript not being able to send keystrokes


  Go to System Preferences --> Security &amp; Privacy --> Accessibility. From there delete the application and add it again.


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More Info

Sending Keystrokes:
How to send special keys Applescript, How do I automate a key press in AppleScript? and List of Apple Key Codes

Fixing applescript not being able to send keystrokes: Application is not allowed to send keystrokes