Seemingly this is an observational (correlational) study, not an experimental study.
Therefore you can not examine effects of Instagram use, just statistical associations.
Low satisfaction could motivate Instagram use, or both could be effects of third factors.
Or, did you include additional variables in your study which could help examine such
By the way,information about sample size is missing.
Since Instagram use is measured on an ordinal scale, you could use Spearman rank
correlations to analyse its relationship with age group and with satisfaction, respectively.