Hi felixtae. I know two counters at DXB that will activate your skywards card to become e-gate functional.

In T1, outside (!) the check in area is a food court area. To get there, you need to go up the stairs. The food court sits basically on top of the check in desks that are below. The e-gate is close to the food court and is usually quite empty. Do this before you check in.

In T3, I only know the one in the premium check in terminal. So you pass immigration but before (!) you got through security you will find a small booth for the e-gate. Here, they also can enable the skywards card to become e-gate active. I have often found the booth unmanned, e.g. when I come late at night, i.e. past midnight, for a departure in the 2-3am bank.

I have the feeling that there must be another e-gate counter at T3 Eco terminal.