Haven't received Serial Number or Authorization Code and can't seem to get in contact with Sketchup/Trimble?

Yes there is an issue. 2017 needs a classic license.
You would need to contact Sales and buy a 2017 specific classic license, if they will sell you one.
Subscription is 2019 and up.
@colin might be able to set something up for you.

Why would you not want to use the most up to date version?

2017 Make is the last free version.