PSE 14: software won't open post PSE 2020 trial; Amazon download serial number location

Hello

1. After uninstalling the trial version of PSE2020 my existing copy of PSE 14, which was bought & downloaded from Amazon UK, won't open on my iMac (Catalina 10.15.6). For reference, 2 screenshots of the PSE14 contents on my iMac are attached. 

2. I can find the Amazon order number but there's no record in it for the serial number for the associated download. 

II: update: contacted Amazon who indicated where the product code is and that the software can be redownloaded. Just tried that and received this message:  

Any help to resolve either issue will be much appreciated, thankyou.  

Background: 

In 2015 I bought & downloaded PSE 14 from Amazon UK to my iMac. 

In early 2020 I downloaded a month's trial version of PSE2020.  I subsequently received an Adobe popup message offering to extend the trial for 3 months which I did.  Deciding to stick with PSE14 I uninstalled the PSE2020 trial version. Since then I'm unable to open my copy of PSE 14. 

I've checked my Amazon order & it doesn't contain the download serial number & the Adobe webpage that explains how to find a serial number from an Amazon purchase is broken, viz:

https://helpx.adobe.com/uk/download-install/kb/redeem-code-for-elements.html