There is an error here, but it is not what you think it is.

To in this case is not the ‘infinitive marker’, which sits in front of an infinitive (what you call the ‘verb-zero or –general’), but the ordinary preposition to, which may very well take a gerund (the -ing form acting as a noun) as its object.

Unfortunately, it’s the wrong preposition—or at least it used to be.

When I was young, fifty years ago, one said there is an advantage in or of this that or the other. This was distinct from the advantage to the person who received the benefit. Your example would have been written (with the to phrase added) as:

There are two main advantages to many employees in working in teams over working alone.

In colloquial use, however, the construction with to instead of in has been common for a very long time; and I have no doubt that it will eventually be accepted in formal use, if it has not been already.

But I recommend that you maintain the distinction. That way you will never raise anybody's eyebrow, not even that of old fogeys like me; and you will avoid the repetition if you ever have to say something like:

^?There is an advantage to you to maintaining the distinction.

That's awkward. It's much more graceful to say

There is an advantage to you in maintaining the distinction.

^? marks an utterance as marginally or only possibly acceptable

There is an error here, but it is not what you think it is.

To in this case is not the ‘infinitive marker’, which sits in front of an infinitive (what you call the ‘verb-zero or –general’), but the ordinary preposition to, which may very well take a gerund (the -ing form acting as a noun) as its object.

Unfortunately, it’s the wrong preposition—or at least it used to be.

When I was young, fifty years ago, one said there is an advantage in or of this that or the other. This was distinct from the advantage to the person who received the benefit. Your example would have been written (with the to phrase added) as:

There are two main advantages to many employees in working in teams over working alone.

In colloquial use, however, the construction with to instead of in has been growing more and more common for the past three quarters of a century; and I have no doubt that it will eventually be accepted in formal use, if it has not been already. Here's a Google Ngram:

But I recommend that you maintain the distinction. That way you will never raise anybody's eyebrows, not even those of old fogeys like me; and you will avoid the repetition if you ever have to say something like:

^?There is an advantage to you to maintaining the distinction.

That's awkward. It's much more graceful to say

There is an advantage to you in maintaining the distinction.

^? marks an utterance as marginally or only possibly acceptable