Study the information about adverbs of manner.
Adverbs of manner tells us how something happens.
How did Jake behave? He behaved badly.
Adverbs of manner often have -ly.
The train went slowly.
Other examples of adverbs of manner without -ly:
Better, best, early, high, hard, last, late, monthly, near, wide, worse.
Some adverbs have 2 forms but the meanings are different:
The team played hard. (positive meaning)
The team hardly played at all. (negative meaning)
If you need to use these words as adverbs, you should say in a + adjective + way/manner/fashion.
Some adjectives end in -ly: friendly, lively, lovely, sickly, silly, motherly, cowardly.
Miss Brown always greets us in a friendly way.