Cannot activate or use SU 2018

A user of ours wants to add a license, but the application keeps on prompting offline.

They already tried using a mobile hotspot, turned off firewall and disabled antivirus, but the same offline display.

“Bummer, It looks like you’re offline”

“It looks like you might be offline”

This is issue is encountered in Sketchup 2018.

Any suggestions will be a big help.