Cannot use digital certificate with Adobe Reader without a PIN or password

I assume your digital certificate is packaged together with the associated private key in a PKCS#12 (aka PFX) file. This indeed can be done without password protection.

Adobe Acrobat currently expects PKCS#12 files to be password-protected, though.

Thus, consider recreating your PKCS#12 file with password protection for use in Acrobat.

You can do so using openssl but there also might be more simple programs to do so.

​@PereC unfortunately, you will need a PIN or password to open it. There is a reason why it’s look for security. If you don’t know it, ask the person for it. You could try 00000 or 11111. But, I highly doubt that would work

There are online tools that can unlock it, but if it’s locked for a reason, think about the security. Online freebie sites may use your personal iD numbers for the wrong reasons