The surface should not have become sticky, which may be due to not wiping off all the surplus oil as the instructions say to do. You have to be very thorough doing this with any oil or "oil finish" because no oil should remain on the surface. Any oil that is left will either remain liquid or turn gummy/sticky. None will ever properly harden.
Now that you have the issue this is one of those things where there's no clear course of action, you have a number of options all of which are a bit messy and take a bit of time but don't worry, you will be able to salvage the tabletop.
Sanding to remove the sticky residue on the surface is one way to rectify the problem, although it can use quite a bit of paper because the oil and wood dust can clog it very quickly. Scraping with a suitable tool is a much better approach if someone already has experience in using a scraper on wood.
If you don't mind the smell and the mess it may not be too late to remove excess partially-dried oil with mineral spirits (UK: white spirit) or if you prefer, turpentine. You'll need to use plenty of cloths or paper towels soaked in the solvent to work away at the surface until all trace of the oil has been removed.
Unless you have a suitable respirator it would be best to do this outdoors, if you must work indoors do it beside an open window or outside door if possible.
Safety note: these wiping cloths represent a potential fire hazard so to be on the safe side either leave them flat on the ground outside to dry off after use, or stuff them into a glass jar partially filled with water and close the lid.
When you think you've done enough leave the wood to dry off for about 15 minutes to an hour and then run your fingers over it looking for gummy patches. If none remain you've successfully cleaned off all the excess oil from the surface and can resume finishing.
Assuming you want to continue to use the Behandla the instructions in this previous Answer should be of help in achieving a better result.
My advice to Ikea purchasers would be first not to buy the Behandla oil just because you're in Ikea and they sell something that can be used on wood.
Look at what you actually want in your finish for colour, level of protection, odour, drying time etc. then decide based on that what to use. This could be anything, including leaving the wood bare, a soap finish, waxing, oiling, shellac, "Danish oil", a waterbased finish, varnish, even a pour-on epoxy if you want a super-tough glassy surface (these are listed roughly in ascending order of protection).