Will I bear a sin due to the profile pictures (avatars) of unveiled women for the foreign group members who express gratitude for the educational content I provide, knowing that the group is beneficial and a source of livelihood?

If there are no Shariah violations in the group's content and its administrator manages it, then there is no harm in creating it. It is permissible to earn money from the notes published therein if it is beneficial knowledge and does not infringe upon the rights of others. There is no harm in having pictures with minor display of adornment (tabarruj) due to its widespread prevalence, and because it is not intended, and "what is permissible dependently is not permissible independently."