I posted in a different thread about the problems with the digital credential. The bottom line is that it is NOT yet ready for prime time. I recommend avoiding it.
There are two primary reasons for this:
1. The roll-out was spotty - VERY spotty. It is difficult or impossible to know where you might be able to obtain a digital sello. The concept was for every Camino related establishment along all the Caminos to have a standard sign with a QR code for you to scan. That would transfer, tine and date stamp the imagine of that place's rubber sello to your smart phone. But, there was little follow through to determine which establishments had obtained a QR label and which did not. This was intended to stop the handling of the ubiquitous rubber stamps and ink pads along the Caminos - as this was considered a vector for spreading COVID.
2. The Pilgrim Office cannot read the digital data on your smart phone. They have no method to unlock the digital sellos.
The take away is to continue to use the old fashioned rubber stamps sellos. Remember to use alcohol based hand sanitizer afterwards.
Hope this helps.
Tom