I am an experienced Scrum Coach and an Agile Coach. I like to pass on my knowledge and experience in workshops "from practice for practice" and at universities.
The most important requirement for an agile project is that you are willing to accept the changes in the way you work that it will involve. If your project is implemented agilely according to Scrum by an external agency, you don't have to change your entire way of working or let your entire company work agilely - that often wouldn't really make sense either.
Before you started looking for an agency, you may have already thought about it in detail, taken the trouble to talk to the management, and finally wrote a briefing describing your project.
Agile working according to Scrum is essentially determined by communication. So also by everyone developing an understanding together of how this should and can look like - and also what restrictions there may be, what conflicting interests. It may well be that two people or departments in your company have very different ideas about your project.