having the same issue, first time using SLS so this caused massive confusion. Anyways, tried copying the repo and renaming the folder from board_arduino_tft_espi-1.1.0 to arduino_tft_espi_v1_1_0 and places in \Documents\SquareLine\boards\Arduino folder, this allowed me some progress but still being prompted about downloading boards, the project opens but now I am not sure if the error while exporting my project is either my fault or this bug… frustrating experience.