Am I asking too much?

I was a solo admin before leaving and joining a team at a larger company. In my previous position, my predecessor was absolutely the most helpful she could be, right down to providing a transition document and recommendations for the future. She was friendly and communicative. New job, not so much with the niceties.

Currently, my team consists of me and another admin. The org is extremely complex, over 1000 users, and we use third-party apps I've never used before. I know Salesforce and how to find answers to Salesforce problems (and even some third-party app problems). But I feel like I've been thrown into the deep end with zero training and am expected to sink or swim because my colleague is "too busy" to train me properly and expects me to just figure things out. Resolving cases obviously takes longer because I often don't know where to begin with all of the complexity. My colleague is, again, so busy, that getting help from her is difficult and usually not on time.

Is this the norm? Am I expecting too much to be trained on these third-party systems? I could understand if it was a situation where the admin left before I was hired and there was no one for transition. Clearly, I'm on my own and don't really expect any help. Not sure how to handle this moving forward. Any advice?