Friend’s sister got a credit card activation code sent to her phone. Is the sister scamming my friend?

Une personne soupçonne sa sœur d'utiliser son nom pour ouvrir une carte de crédit et demande conseil pour vérifier si c'est le cas.

My friend (M) got a code sent to her phone recently that her sister wanted her to send straight away. After searching it up, M saw it was a company called ‘Zilch’ that gives out credit card loans. She sent her sister the code, and told me today. Alarm bells instantly started ringing, because I know M’s sister is in pretty dire circumstances and needs money. M has been giving her sister money for a long time, her sister will often ask and promise to pay it back, saying she will be evicted, have no electricity etc. and never pays it back. M is obviously frustrated by this, but (in my opinion) has a blindness to it and ultimately wants to help her family. She doesn’t give her money when she can’t afford it. I’m pretty sure the sister is setting up a credit card in M’s name. She’s asked M to do it before and M said no, and she let it go. There has been suspicions before in the family that the sister is using people to set up credit cards, but the sister vehemently denied it. What I want to know Reddit, is how does M check if this is the case? I know nothing about finance, but I think M keeping up with her credit score is a good start. We will also probably contact Zilch’s customer service and see.