Followed instructions outlined here: https://www.lansweeper.com/knowledgebase/how-to-configure-ssl-in-iis-express/
1. Didn't change default http and https ports. (Still 81 and 82 respectively)
2. Imported the wildcard certificate that I would like to use to both the "Local Machine" certificate store and "Current User" certificate store under (Personal > Certificates).
3. Grabbed the thumprint and put it in the correct fileds in "Program Files (x86)\Lansweeper\IISexpress\IISExpressSvc.exe.config"
4. Changed the UseCustomSSLCertificate value to 1 in the same file.
5. Started IISExpress. HTTP site works, HTTPS site gives me this error in FF: