disconnect the dongle from the host
double-click button on the dongle (through the tiny hole)
copy logitacker_apr-dongle.uf2 to the removable drive 'NRF52BOOT'
The actual process was:
To program the dongle follow these steps:
disconnect the dongle from the host
hold the button on the dongle (through the tiny hole) while plugging into the host
copy logitacker_apr-dongle.uf2 to the removable drive 'NRF52BOOT'
The README states:
The actual process was: