Only .ovpn files are supported in the UI.
Follow this guide on how to merge the ca, cert and key files into the ovpn file:
If you open your cert file and you see blocks like this:
-----BEGIN CERTIFICATE-----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-----END CERTIFICATE-----
Then you can ignore the part of converting in the guide linked, just paste those blocks.
Your config should look like this:
Blame your provider for not using the latest method of creating config files 