Is anaconda free for 1,000 people working in a company who use it for private study outside of work?

As Terms of Service on the official website (in parentheses, it is not a "commercial activity" at all, so it is free of charge wherever you belong.

To avoid confusion, "commercial activities" are any use of the Repository which is NOT:
(To avoid confusion, the use of a repository that does not fall under any of the following is "commercial activity")
* use soly by an individual using for personal, non-business purposes
(*Personal use by independent individuals, not for business purposes)

However, the boundary between individual activities and corporate R&D activities is very vague.
If there is a possibility of a shift to the development of a company's products in the future, it is safest to contact them as per the terms of use.

Please reach out to us for confirmation or to apply for a fee exception for search usage by visiting https://....Approval is at the sole description of Anaconda.
(Please contact us at https://... for confirmation or free application for research purposes.Anaconda will approve it on its own.)

As it is stated that Anaconda will make its own decision on whether it is charged or not, if the free user's decision is incorrect and it is judged to be a commercial activity, the appropriate action may be taken.
Please note that this answer is also an individual interpretation of the respondents and may not be correct.

Reference:
[Programming] Anaconda's fee-based avoidance and alternatives