Cantaloupe or squash plants have male and female flowers.

Females have a small bulge beneath the flower, which will turn into a fruit once pollinated. Female flowers have a short stigma, while male flowers have a long stamen

Sometimes, your plant will have a lot of male flowers, but no female ones. Without female flowers, the plant can’t produce cantaloupe or squash. Male flowers will appear first, with female flowers appearing later.

Excessive rain or high temperatures can also cause cantaloupe or squash to not produce female flowers. The ideal growing range is between 65-95 °F (18-35 °C). If it gets hotter than this, the cantaloupe or squash vine might only produce male flowers. If you have a lot of male flowers, you need to wait until female flowers appear.

Some cantaloupe or squash plants will also have some “perfect” flowers, flowers with both male and female parts. These flowers are usually self-pollinating.

The most common reason why cantaloupe or squash will flower but not fruit is that the female flowers aren’t getting pollinated.

Bees are the most reliable way for your cantaloupe or squash to be pollinated. You can encourage bees to stay in the area by planting flowers that bees are attracted to and by avoiding the use of pesticides or insecticides.

You can also pollinate your cantaloupe or squash by hand. It’s best to do this early in the morning, on a day when it isn’t raining.

Identify the male and female flowers on your plants. Using a small paint brush gently swab the inside of the stamen on a male flower, moving in small circles to cover the brush in pollen. Then, take the pollinated brush to the stigma of a female flower, and gently brush the pollen all over. One male flower can pollinate multiple female flowers depending on how much pollen you have on your brush.

Repeat this process as more flowers appear on the plant. Soon you should notice the bulge at the base of the female flowers starting to grow larger and turn into a fruit. 

See the almanac link below for pictures and YouTube video on how to hand pollinate.
https://www.almanac.com/why-my-squash-not-fruiting