If the device is compatible to be activated with us, the system will re-direct you to another screen to order the SIM card. Once you receive it, try to swap phones online or reach us back here so we can help you further.
If you go through the threads here there are many confirmed S10e/S10/S10+ working on Boost that come unlocked from Samsung and, even though they seem to be denying it even Sprint branded ones bought from Samsung. Looks like it is easier to buy regular unlocked from Samsung and then buy the Sim card either from Boost online afterward or buy it from a local Sprint or Best Buy store if they have them in stock. The sim card is SIMOLW516TQ it comes in a 4 pack usually Sprint branded if you get it from Best Buy worked for my unlocked S10+ from Samsung.