Specific Question About Spell Saves (moonbeam specifically).

I am not sure if this is me doing something wrong(I am new to D&D and Roll20) or Roll 20 being weird. First question how does moon beam work with the spell save. It say the creature hit makes a Constitution save. To figure out what the creature need to beat we take 8 + PROF + CON(from the Druid), Right? The Druid's spellcasting modifier is Wisdom, but that doesn't matter in this case right? If this is correct Roll20 keeps saying DC 10 to save when the spell is clicked on when it should be DC13 (Druid's CON is 3). What am I doing wrong?

the target is making a constitution save vs the druids spell save, which is always going to be based on the druids wisdom, no matter what the save is based on. so if we assume the target is a level 1 with a con of 20 and prof. in con saves and the druid is a level 1 with a wis of 20, the target would roll 1d20 + 5 for con + 2 for the prof. bonus vs the druid's base of 8 + 3 for the wis of 16 + 2 for prof for a total DC of 8+3+2, or 1d20+7 Con Save vs DC 13.

Have you set the spell casting ability on the sheet? Sounds like it is only adding the prof to the save.