Registration information will be available soon. The conference will be hybrid, conditions permitting. It will be possible to attend the conference virtually if you choose. The cost of virtual participation will be lower than physical participation, but we are still finalizing the exact details.
For reference, ICIDS 2020 was fully virtual: https://icids2020.bournemouth.ac.uk/#buy-tickets, and ICIDS 2018 was physical: https://icids2018.scss.tcd.ie/register.html (but note that this only shows the late registration fees, early registration was lower), so these can provide rough estimates of the fees.