For this one, remember つごうがいい for now and ignore the Kanji; then get exposure, perhaps read things with Furigana.
Yeah, for the Kanji, despite 都 does have an On’yomi of つ, I can recall only one more word using this reading, 都度, which isn’t in WaniKani.
On’yomi for 合 shouldn’t be much of a problem.
Also, let me link the said beautiful explanation My silly rant about 合 - #24 by Jonapedia