This could have been the TDAC it’s an electronic arrival card you must fill out on line with three days up to arrival, you get a confirmation email with a QR code, this automatically show on their systems if she hadn’t done it they may have been asking for this.
The Multi entry tourist visa is not 90 days it’s 60 days for each visit which you can extend 30 days, then you have to leave the country, then you get 60 again when you return. Check the validation of your visa if Multi then this should be 6 months.