During encapsulation process:

For the encapsulation process, your cells can be in suspension in normal media conditions (e.g. DMEM, MEM, RPMI, etc. supplemented with FBS and antibiotics).

After encapsulation process:

After encapsulating your cells and making the gel discs (see how in this video), place them into pre-warmed culture media. The media should be replaced after 2-3 hours incubation and then according to your experimental conditions. Always make sure that gels with the encapsulated cells are submerged and not floating on the surface. 

Regarding the type of media, QGel recommends the media that you would normally use. Because QGel is largely made of liquid in the polymer matrix, the media will quickly diffuse into the gel disc and provide your cells the nourishment they need. Note that, when cultured in 3D, certain cell types will require significant amount of serum (e.g. 10% FBS) to be able to spread and grow nicely.