That's just using each character as a number. Did you try converting it to the binary representation? for example, 11 in base-62 equals the number 63
I unfortunately have to leave right now, but my prediction is that if you took z69JZqlJn862D1ndx7oLVEMmV0lP1zewEeUCrsI7Roahzpeny7P and converted it to the binary representation, assuming that's base62, you'd get a dogecoin private key.
Thanks but we are not looking for a Doge priv key.
We have an existing Bitcoin address which is funded so that does not make much sense.