Please follow the steps below to convert your SSL certificate into a PFX format:

1) Load this URL:
https://www.sslshopper.com/ssl-converter.html

2) Select “Type of Current Certificate” -> Standart PEM and “Type To Convert To” -> PFX/PKCS#12

3) Attach Private key, CA intermediate certificates, and .CRT ( certificate). This can be obtained from the client area, under Services.

4) Type the password for the .pfx file Or just ignore this option

5) Click on Convert and you will receive the file.

Copy it to your server, and Import it to your server, it should be working.