What happened in the KP garden (it sounds like as part of a rehearsal) was a private exchange of vows they'd devised themselves and a blessing by the Archbishop. It was in no way, shape or form a wedding, legally or in religious terms. Fine that they did something private and meaningful, good on them, but Meghan went wrong by describing it as " we got married" 3 days before without qualifying it, because they didn't
Meghan is clearly a bit fast and loose with the actual truth, but I do think that here she was trying to imply that actually they were already “spiritually” married rather than legally. It is still problematic, however because she definitely used the words “we were married” which obviously quite reasonably can be interpreted as in the legal sense.
My biggest issue with it is that she seems to be implying that their actual legal marriage had no real meaning for her and was just for show. That struck me as incredibly ungrateful and rude and as though she was trying to show that they were somehow superior by having this private thing with the Bish a few days before. It came across as sneary and condescending
But no, they didn’t get married three days before they got married. And as pp have said, they could have easily avoided “the spectacle” by having a small wedding. But that wasn’t really what they wanted. Until they thought they could seem superior by saying they did