How do I log in to Apple ID when I keep getting a password error message despite having updated it on iphone?

My new macbook air is being repaired. I'm trying to use my older one but it has OS X Yosemite and can't update programs I need to use. I'm trying to download OS X Catalina but it asks for my apple ID password, despite having reset it and entered it multiple times it keeps giving me an error message saying my password is incorrect. My phone is giving me a passcode to enter but there is no prompt on the macbook where I can enter it. I've tried multiple times. Have also tried restarting computer but that didn't work either. (yet it let me log in to post a question here so I thought I resolved it but when I tried again to log in to download Catalina I got the same error message of incorrect password).