They are the two halves of what a QR code contains. The SM-DP+ address is the server your phone fetches the profile from; the activation code identifies your particular eSIM on it.
Phones that ask for two fields want them separately. Phones that ask for one want the whole activation key, which is both of them joined together.
All three forms are on your order page, each with a copy button. Treat them as private: anyone who has them can install your plan.