Stressed about a first job.

Hi,
I got recently hired in a small security firm. I got assigned to an external pentest of a target with over 80 IPs and lotta more domains. Looking at past interactions with this client we mostly found what automated tools find. Its apparently not "our type of work" and we prefer small scope manual work but here I'm.

I've got 4 days for this. What do I do ? It's unlike anything I've ever done and my colleauges aren't very helpful. I'm stressing that if I only report lows/infos I'll get fired after my 3 months test period is over. The company has not outlined any goals and everyone seems to be chill. Am I overreacting? I worked physically before and my labour2reward ratio is raising alarms.