PGP Public Key To long - Encryption Desktop

Good Morning,

I recently got set up with PGP on Encryption Desktop and am getting set up with a government account. They requested a text file of the key, which I sent over. The only problem is that the person who I sent it to said that they key was too long for them to use and has to be under 4000 characters.How would I go about "shortening" the key or "compressing" it. Any help would be much appreciated. Thank you