Code signing woes

It is time for our ‘annual’ renewal, but the directions seem to no longer work the way they did last year, and the various chat/help people’s help doesn’t seem to ‘advance’

They say to use either IE, or Edge in ‘IE’ mode for various steps, whilst we can get .cer or .crt files trying to install them using ‘digiCertUtil’ gives
“The private key for this certificate could not be found on the machine or current user key stores”
Installing using MS type tools says ‘ok’

I have the private key as a text file, but, well, what to do with it to make it happy?

If I follow their ‘export from IE/Edge’ instructions the ‘Export Private Key’ message does not come up for this year’s certificate, and this exporting a .PFX is not possible.

Any ideas?