The team is singular. It is one thing. However, it's not just in the present perfect progressive that you'll run into this distinction. For example, consider this sentence in the present tense: "The team prepares for an important match taking place on Sunday." You wouldn't say "The team prepare for an important match taking place on Sunday," because the team is one unit. It's singular. When you talk about the team itself, you are talking about "it," which is singular. You would use "they" to refer to the actual members of the team: "The team members prepare for an important match taking place on Sunday."

For another example: "France wanted its land back before it would sign the treaty." Again, even though France refers to all the French people, the country of France itself is one singular object. You wouldn't say "France wanted their land back before they would sign the treaty." However, if you wanted to use the plural form, you could say "The French people wanted their land back before they would sign the treaty."

For an example in the present perfect progressive: "The committee has made a decision regarding the deal." Though there are multiple people on the committee, the committee itself is one object, so it's singular.

This is a common misunderstanding that even native English speakers often have trouble with, so don't be discouraged if you don't spot the usage at first. Just keep reading, writing, and practicing, and you'll be able to tell when to use the singular/plural forms in any tense. ;)